The use of a top drive technology has led to substantial improvements in efficiency and safety in drilling over the past 15 to 20 years. By contrast, methods for running casing, even with top-drive technology, have remained relatively unchanged. Traditional methods of running casing require the use of a special teams employed solely for the purposes of running casing, at significant cost to the driller. Additionally, these teams must be brought in, thus slowing the drilling process.
Power tongs are an established method to run casing in coordination with the drilling rig hoisting system. The power tong method allows the pipe segments to be mated with threaded ends between sequential segments as they are added to the string being installed in the well bore (or removed and disassembled). The power tong method, however, does not support other beneficial functions such as allowing the casing to be filled while moving the pipe. Previous methods and equipment do not include a tool that can run casing while serving other beneficial and time saving functions. For example, filling the pipe with fluid and the tool doubling use as a circulating tool to replace the fill tube when desired.
With top-drive technology coming into the drilling arena, drilling rigs equipped with top drives have enabled new methods of running casing and other tubulars. The top drive can be equipped with known running tools to grip and seal between the proximal pipe segment and the top drive quill (wherein quill is meant to include drive string components that may be attached, the distal end effectively acting as an extension of the quill).
Various devices have been developed to accomplish top-drive running casing. These devices are used in coordination with the top drive and allow rotating, pushing, and filling of the casing string with drilling fluid while running, thus removing the limitations of the power tong method. Simultaneously, automation of the gripping mechanism combined with the inherent advantages of the top drive reduces the necessity of a specialized team of skilled personnel who are being compensated for hard labor in sometimes hazardous conditions. These devices, with their independent operation without associated personnel, allow for increased safety and efficiency.
To handle and run casing with these top drive tubular running tools, the string weight is transferred from the top drive to a support device when the proximal or active pipe segments are being added or removed from the otherwise assembled string. This function is typically provided by an “annular wedge grip” axial load activated gripping device that uses “slips” or jaws placed in a hollow “slip bowl” through which the casing is run, where the slip bowl has a frusto-conical bore with downward decreasing diameter and is supported in or on the rig floor. The slips then acting as annular wedges between the pipe segment and the proximal end of the string and fusto-conical interior surface of the slip bowl, tractionally grip the pipe but slide or slip downward and thus radially inward on the interior surface of the slip bowl as string weight is transferred to the grip. The radial force between the slips and pipe body is thus axial load and self-activated or “self-energized”, i.e., considering the tractional capacity the dependent and string weight the independent variable, a positive feedback loop exists where the independent variable of string weight is positively fed back to control the radial grip force with conotonically acts to control tractional capacity or resistance to sliding, the dependent variable.
Similarly, the torque applied to the active pipe segment must also be reacted out of the proximal end of the assembled string. This function is typically provided by tongs which have grips that engage the proximal pipe segment and an arm attached by a link such as a chain or cable to the rig structure to prevent rotation and thereby react torque not otherwise reacted by the slips in the slip bowl. The grip force of such tongs is similarly typically self-activated or “self-energized” by positive feedback from the applied torque load.
Multiple documents describe tools that can be used to run casing with the use of a top drive. For instance, U.S. Pat. No. 8,042,626 describes such a tool for use with a top drive that allows for rapid engagement, release, hoisting, pushing and rotating. The casing is engaged within the tool through rotation that is assisted by hydraulics.
However, no tool has been shown to work with the top drive, which is simple, requires no outside energy source, and maintains the integrity of the casing. Thus, there is a need for a casing tool that employs the top drive and is easily used, removing the need for personnel to run casing. A self-activated tool would be particularly advantageous; requiring no outside energy source for its proper function.